The present invention relates to a device for inductive energy transfer from at least one emitter coil to at least one receiver coil which is spaced apart from the emitter coil, comprising a device for improving the coupling in the case of an offset between the at least one emitter coil and the at least one receiver coil.
Electric vehicles and hybrid vehicles usually have an electrical energy accumulator, for example, a traction battery, which provides the electrical energy for driving. If this electrical energy accumulator is completely or partially discharged, the electric vehicle must head for a charging station, at which the energy accumulator can be recharged. To this end, it has been commonplace up to now at such a charging station that the electric vehicle is connected to the charging station by means of a cable connection. This connection usually must be manually established by a user. In this case, it is also necessary for the charging station and the electric vehicle to have a mutually corresponding connection system.
Furthermore, wireless charging systems for electric vehicles or hybrid vehicles are also occasionally known. In this case, an electric vehicle is parked over a coil or a charging pad or charging device. This coil emits a magnetic alternating field. The magnetic alternating field is received by a receiver coil within the vehicle and is converted into electrical energy. By means of this electrical energy, a traction battery of the vehicle can then be charged. Document DE 10 2011 010 049 A1 discloses such a system for charging a vehicle battery, in which the energy is transferred by induction.
In addition, the energy accumulator of the electric vehicle can also be used for reclamation. A cable connection or an inductive energy or power transfer can likewise be used for this purpose.
In the wireless charging of a battery of an electric vehicle, there is always a fixed geometry of the emitter coil. Said emitter coil is integrated and optimized for use in a parking space or, in some systems, in the roadway. The space between the coils is usually air. The disadvantage of this configuration is that the magnetic coupling factor between the two coils is very small, and therefore a high reactive power in the power electronics of the transfer must be overcome.
There is a need for a device, therefore, by means of which the coupling factor between the coils of the inductive charging system is improved.